As part of the Art line within Sigma's Global Vision series, this lens is designed to achieve truly notable optical performance and is ideally suited for creative and artistic applications. Wide-angle lens is designed for full-frame Sony E-mount mirrorless cameras but can also be used with APS-C models where it provides a 52.5mm equivalent focal length. Bright f/1.4 maximum aperture is particularly well-suited for working in available light conditions and provides extensive control over depth of field for isolating subject matter with selective focus. Lens Construction: 15 elements in 11 groups, including one FLD low-dispersion element, one ELD extra-low dispersion element, two SLD special-low dispersion elements, and two aspherical elements. A Super Multi-Layer Coating has been applied to lens elements in order to minimize lens flare and ghosting and contribute to producing contrast-rich and color-neutral imagery, even in backlit conditions. Resistance coating allows oil and water to be easily wiped from the front lens surface and prevents oil and fat from sticking for easy cleaning. Integrated stepping motor realizes quick and quiet internal autofocus, which is further complemented by an optimized AF algorithm to produce smoother focusing performance. Face and eye detection supported in feature enabled cameras. Manual aperture ring can be de-clicked for smooth, silent aperture switching to benefit video applications. Additionally, a dedicated aperture ring lock switch can also be employed to prevent accidental shifting of the aperture setting. Built-in Autofocus-Lock (AFL) button which can be assigned additional functions widens the range of operations available on the lens. Rounded eleven-blade diaphragm contributes to a smooth and pleasing bokeh quality. Weather-resistant construction with a brass bayonet that affords improved mounting accuracy and rigidity.